Heat exchangers

ABSTRACT

A heat exchanger embodying an elongated tubular member with integral fins, in the form of spines, projecting outwardly therefrom in rows, with the transversely adjacent fins in adjacent rows being disposed different distances from an end of the tubular member.

' United States Patent Pasternak 1 July 17, 1973 [5 HEAT EXCHANGERS3,229,722 l/1966 Kritzer .1 132 39 K [75] Inventor: Stephen F.Pasternak, Park Ridge, 33 1 5 3 [73] Assigneez 2:321:82 ofilAmerlca,Incorporated, Primary Examiner charles J Myhre g AssistantExaminerTheophi1 W. Streule, Jr. [22] Filed: Aug. 27, 1971 AttorneyRoot& OKeeffe [21] Appl. No; 175,675

B TR [52] US. Cl. 165/181, 113/118 B, 29/1573 B [57] A 8 ACT [51] II}!-Cl F281 l/20 A heat exchanger embodying an elongated tubular [58] Field01 Search 165/181, 182, 179; member with integral fins in the form ofspines 29/1573 B; 113/118 B; 138/3 jecting outwardly therefrom in rows,with the transversely adjacent fins in adjacent rows being disposed [56]References C'ted different distances from an end of the tubular member.

. UNITED STATES PATENTS 3,202,212 8/1965 Kritzer 165/179 11 Claims, 5Drawing Figures Patented July 17, 1973 HEAT' EXCHANGERS BACKGROUND OFTHE INVENTION This invention relates to heat exchangers and, moreparticularly, to heat exchangers of thetype embodying outwardlyprojecting fins.

It is a primary object of the present invention to afford a novel heatexchanger of the finned type, and a novel method of making such a heatexchanger.

Another object of the present invention is to afford a novel finned heatexchanger, wherein the fins are formed by cutting or gouging them fromwall portions of the heat exchanger.

Another object is to afford a novel finned heat exchanger wherein thefms are formed by cutting or gouging them from the ribs of ribbedtubular stock.

Heat exchangers embodying spines formed from outwardly projecting ribson a tubularrnember have been disclosed in R. W. Kritzer United StatesLetters Patent Nos. 3,202,212 and 3,229,722. Heatexchangers of the typedisclosed in the aforementionedKritzer patents have proven to be veryeffective. However, it is an object of the present invention to affordimprovements over heat exchangers of the type disclosed in theaforementioned Kritzer patents.

Another object of the present inventionis to afford a novel finned heatexchanger having fins in the form of outwardly projecting spinesconstituted and arranged in a novel and expeditious manner.

Another object of the present invention is to afford.

a novel finned heat exchanger which is practical and efficient inoperation and which may bereadily and economically producedcommercially.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show' preferredembodiments of the present invention andthe principles thereof and whatI now consider'to be the best mode in which I have contemplated applyingthese principles. Other embodiments of the invention embodying the sameor equivalent principles may be used and structural changes may be madeas desired by those skilled in the art without departing from thepresent invention and the purview of the appended claims.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view of a length of heat exchanger elementembodying the principles of the present invention;

FIG. 2 is a fragmentary, side elevational view of a portion of the heatexchanger element shown in FIG.

FIG. 3 is an enlarged, somewhat diagrammatic, fragmentary, sectionalview taken substantially on the line 3-3 in FIG. 1;

FIG. 4 is a perspective view similar to FIG. 1, but showing a modifiedform of the present invention; and

FIG. 5 is a fragmentary, side elevational viewof a portion of the heatexchanger element shown in FIG. 4.

DESCRIPTION OF THE'EMBODIMENTS SHOWN HEREIN the drawings as one endportion of an elongated tubular member 2, to illustrate the presentlypreferred embodiment of the present invention, and to illustrate thepresently preferred method of making heat exchangers in accordance withthe principles of the present invention.

As will be discussed in greater detail hereinafter, in the preferredpractice of the present invention the heat exchanger element 1preferably is formed from a suit able length of tubular stock, such asthe tubular member 2, working from one end portion A of the tubularmember 2,. FIG. 1, toward the other end B thereof, and severing the heatexchanger 1 from the remainder B-C of the tubular member 2 uponcompletion of the forming ,of the desired length of heat exchanger, suchas, for example, the length A-C.

Theheat, exchanger element 1 embodies, in general, an elongated tubularbody portion 3 having elongated fins 4, 5 and 6 projecting outwardly, inrows, from elongated, outwardly projecting ribs 7, 8 and 9,respectively, which extend longitudinally of the tubular member 2 inparallel spaced relation to each other. Each of the fins 4-6 embodies anelongated base portion 10 and an outer free end portion 11. As will bediscussed in greater detail presently, the fins 4-6 are formed from thetubular body member 2, and the base portions 10 thereof are integralwith the adjacent, underlying portion of the-tubular body portion 3 ofthe finished heat exchanger.

The tubular'member 2 shown in the drawings is substantially rectangularin transverse cross section, embodying a top wall 12 and a bottom wall13 disposed in substantially parallel relation to each other, and twooppositely disposed side walls 14 and 15 extending between therespective longitudinal edges of the walls 12 and 13 in substantiallyperpendicular relation thereto. Openings 16 extend longitudinallythrough the tubular member 2. As will be appreciated by those skilled inthe art, the tubular member 2 is shown in FIGS. l-3 as being rectangularin transverse cross section and as having a plurality of openings 16extending therethrough merely by way of illustration and not by way oflimitation, and tubular members having shapes other than rectangular andhaving a single opening extending longitudinally therethrough may beafforded without departing from the purview of the present invention.

The tubular member 2, from which the heat exchanger 1, shown in thedrawings, is made, may be formed of any suitable material, such as, forexample, aluminum, and, preferably, in addition to the three ribs 7-9,which project outwardly from the top wall 12, embodies three similarribs 17, 18 and 19 on the bottom wall.l3.

ples of the present invention, is shown in FIGS. l-3 of In making theheat exchanger 1, a tubular member such asthe tubular member 2, andembodying the ribs 7-9 and 17-19 extending the full length thereof, mayfirst be. formed. Thereafter, the fins 4-6 may be successively formed onthe ribs 7-9 from one end portion of the tubular member 2, such as theend portion A, toward the other end B thereof. The fins 4-6 may be cutor gouged from theribs 7-9, respectively, from which they extend, bymeans of a suitable cutting tool, such as the cutting tool 20 shown inFIG. I.

The cutting tool 20 embodies three elongated cutting surfaces 21, 22 and23, disposed in laterally offset relation to each other in position tobe moved longitudinally of the ribs 7-9, respectively. The two cuttingsurfaces 21 and 23, which are the two outermost cutting surfaces on thecutting tool 20, are disposed in uniplanar relation to each other.Preferably, the cutting edges 24 of the cutting surfaces 21-23, whichare disposed at the lower ends of the respective cutting surfaces 21-23,are disposed in unilinear relation to each other.

In the cutting tool 20, the cutting surface 22, which is disposedbetween the cutting surfaces 21 and 23, projects outwardly to the right,as viewed in FIG. 1, from the cutting edge 24 thereof a greater distancethan the cutting surfaces 21 and 23 project from their respectivecutting edges 24, to thereby dispose the main body portion of thecutting surface 22 forwardly of the cutting surfaces 21 and 23 in thedirection of travel of the cutting tool 20 during a cutting operation,which is from left to right, as viewed in FIG. 1. The cutting surfaces21-23 are of such width, and are so disposed relative to each other,that each may be moved longitudinally along a respective one of the ribs7-9 during a cutting operation of the tool 20.

In the operation of the cutting tool 20, it reciprocates through aseries of spaced cutting strokes from the end A toward the end B of thetubular member 2, with the cutting surfaces 21-23 cutting and raisingfins 4-6 from the ribs 7-9, respectively. Referring to FIG. 3, which isa somewhat diagrammatic view through the rib 8 and one of the fins 5thereon, the fins 4-6 are formed on each of the ribs 7-9, respectively,by passage of the cutting surfaces 21-23, respectively, alongsuccessive, parallel paths of travel, such as the paths of travel 25 and26 shown on the rib 8 in FIG. 3. As the cutting edges 24 move downwardlyalong the successive paths of travel, the main body portions of thecutting surfaces 21-23 turn the metal thus severed from the underlyingrespective one of the ribs 7-9 upwardly into outwardly projectingposition. Actually, because of the spacing of the successive cut lines25 and 26 along the outer surfaces of the ribs 7-9, after the initialtins 4-6 are formed on the ribs 7-9, sloping end portions like endportions 27 shown in FIG. 3, are initially formed upon the outer endportions of each of the tins 4-6. However, the cutting operation causesthe fins 4-6 to compress longitudinally so that, as a practical matter,the tapers 27 substantially disappear on fins of usual thickness, tothereby afford a relatively smooth-sided appearance for the outer endsof the fins 4-6 similar to that shown in FIGS. 1 and 2.

It will be remembered that the main body portion of the cutting surface22 is disposed forwardly of the main body portions of the cuttingsurfaces 21 and 23. Thus, in the formation of the fins 4-6, although thebases 10 of the immediately transversely adjacent fins 4-6 in theadjacent rows thereof extending along the ribs 7-8 are disposed inunilinear relation to each other, the outer free end portions 11 of eachof the fins 5 on the central rib 8 projects forwardly away from the endB of the tubular member 2 a greater distance than the fins 4 and 6 onthe ribs 7 and 9, respectively.

With this construction of the heat exchanger 1, the free end portions 11of the ribs 5 in alternate ones of the rows afforded along the ribs 7-8project forwardly out of uniplanar relation to the fins 4 and 6 disposedimmediately transversely adjacent thereto, to thereby affordobstructions extending transversely across the passageways between thefins 4-6 spaced longitudinally of the body member 3. This constructionis effective to increase the static drop through the heat exchanger 1,

when air flow thereacross is in a direction transverse to the length ofthe surface from which the ribs 4-6 project. It is also effective toincrease the turbulance of the air thus flowing across the heatexchanger 1, and to increase the heat transfer capacity of the heatexchanger 1 for the same volume of air passing across such a surface, ascompared to a heat exchanger construction wherein the immediatelytransversely adjacent fins are all disposed in uniplanar relation toeach other.

After thus forming the fins 4 along the desired length of the tubularmember 2, such as the length A-C, the tubular member 2 may be severedtransversely to its length at the point C to thereby afford a finishedheat exchanger element having fins 4-6 spaced along the length thereof.The heat exchanger 1 is shown in the drawings as having fins 4-6projecting outwardly from only the top wall 12 thereof, and, if desired,it may be so formed. However, if desired, fins, similar to the fins 4-6may be cut from other sides of the tubular member 2, such as, forexample, from the ribs 17-19 on the bottom wall 13.

In FIGS. 4 and 5 a modified form of the present invention is shown, andparts which are the same as parts shown in FIGS. 1-3 are indicated bythe same reference numerals, and parts which are similar to, butsubstituted for parts shown in FIGS. 1-3 are indicated by the samereference numerals with the suffix a added thereto.

The heat exchanger 1a shown in FIGS. 4 and 5 is the same in constructionas the heat exchanger shown in FIG. 1, except that the bases 10 of thefins 4 and 6 disposed on the ribs 7 and 9 are not in alignment with thebases 10a of any of the fins 5a disposed on the rib 8.

In the cutting tool 20a, the entire cutting surface 22a, including thecutting edge 24a thereof is disposed forwardly of the cutting surfaces21 and 23. Preferably, the cutting surface 22a projects forwardly of thecutting surfaces 21 and 23 half the distance that the fins 4-6 arespaced longitudinally of the ribs 7-8, so that the immediatelytransversely adjacent fins 4 and 6 on the ribs 7 and 9 are disposed inuniplanar relation to each other, with the adjacent fins 5a on the rib 8disposed midway therebetween.

With this construction, the transverse passageways afforded betweenadjacent pairs of fins 4 and 6 spaced longitudinally of the ribs 7 and 9are partially blocked by fins 5a disposed midway therebetween, tothereby afford a narrowed, tortuous path through the fins 4-6transversely to the length of the heat exchanger la.

It is to be observed-that although only three rows of fins are shown onthe heat exchangers 1 and 1a, that is merely by way of illustration andnot by way of limitation, and that heat exchangers embodying a greaternumber of finned ribs spaced transversely thereacross may be affordedand formed without departing from the purview of the present invention.Also, if desired, fins in rows other than alternate rows, such as, forexample, alternate adjacent pairs of rows, and the like, may be offsetfrom each other without departing from the purview of the presentinvention.

From the foregoing it will be seen tht the present invention affords anovel heat exchanger of the finned type, wherein the fins are in theform of spines.

Also it will be seen that the present invention affords a novel methodof forming such a heat exchanger.

In addition, it will be seen that the present invention affords a novelfinned heat exchanger which is practical and efficient in operation, andwhich may be readily and economically produced commercially.

Thus, while I have illustrated and described the preferred embodimentsof my invention, it is to be understood that these are capable ofvariation and modification, and I therefore do not wish to be limited tothe precise details set forth, but desire to avail myself of suchchanges and alterations as fall within the purview of the followingclaims.

I claim:

1. A heat transfer element comprising a. a tubular member having anelongated wall,

b. a plurality of fins projecting outwardly from said wall in aplurality of laterally spaced rows,

0. said fins in each of said rows 1. having base portions extendingtransversely to their respective row, and 2. having free end portionsprojecting outwardly of said base portions,

d. said free end portions of said fins in certain of said rowsprojecting toward one end of said wall a greater distance than do saidfree end portions of immediately transversely adjacent fins in the otherof said rows.

2. A heat transfer element as defined in claim 1, and

in which a. said base portions of said fins in said certain rows aredisposed in substantially longitudinal alignment with said base portionsof said immediately transversely adjacent fins'in said other rows.

3. A heat transfer element as defined in claim 1, and

in which a. said base portions of said tins in said certain rows aredisposed in substantially parallel relation to a longitudinal projectionof said base portions of said immediately transversely adjacent fins insaid other rows.

4. A heat transfer element as defined in claim 1, and

in which a. said laterally spaced rows are alternately said cer tainrows and said other rows.

5. A heat transfer element as defined in claim 4, and

in which a. said base portions of said fins in said certain rows aredisposed in substantially longitudinal alignment with said base portionsof said immediately transversely adjacent fins in said other rows.

6. A heat transfer element as defined in claim 4, and

in which a. said base portions of said fins in said certain rows aredisposed in substantially parallel relation to a longitudinal projectionof said base portions of said immediately transversely adjacent fins insaid other rows.

7. A heat transfer element as defined in in which a. said tubularmember 1. is substantially rectangular in transverse cross section, and2. has two substantially parallel outer faces, and

b. said rows of fins are disposed on at least one of said faces.

8. A heat transfer element as defined in claim 7, and

in which a. said laterally spaced rows are alternately said certain rowsand said other rows.

9. A heat transfer element as defined in claim 8, and

in which a. said base portions of said fins in said certain rows aredisposed in substantially longitudinal alignment with said base portionsof said immediately transversely adjacent fins in said other rows.

10. A heat transfer element as defined in claim 8, and

in which a. said base portions of said fins in said certain rows aredisposed in substantially parallel relation to a longitudinal projectionof said base portions of said immediately transversely adjacent fins insaid other rows.

11. A heat transfer element as defined in claim 8, and

in which a. said one face has a plurality of outwardly projecting,substantially parallel spaced ribs thereon, and

b. said rows of fins are disposed on respective ones of said ribs.

claim 1, and

1. A heat transfer element comprising a. a tubular member having anelongated wall, b. a plurality of fins projecting outwardly from saidwall in a plurality of laterally spaced rows, c. said fins in each ofsaid rows
 1. having base portions extending transversely to theirrespective row, and
 2. having free end portions projecting outwardly ofsaid base portions, d. said free end portions of said fins in certain ofsaid rows projecting toward one end of said wall a greater distance thando said free end portions of immediately transversely adjacent fins inthe other of said rows.
 2. turning said fins outwardly into outwardlyprojecting position wherein said free end portions of said fins onalternate ones of said rows project further toward one end of saidtubular member than the free end portions on immediately transverselyadjacent fins in the outer of said rows.
 2. having free end portionsprojecting outwardly of said base portions, d. said free end portions ofsaid fins in certain of said rows projecting toward one end of said walla greater distance than do said free end portions of immediatelytransversely adjacent fins in the other of said rows.
 2. A heat transferelement as defined in claim 1, and in which a. said base portions ofsaid fins in said certain rows are disposed in substantiallylongitudinal alignment with said base portions of said immediatelytransversely adjacent fins in said other rows.
 2. has two substantiallyparallel outer faces, and b. said rows of fins are disposed on at leastone of said faces.
 3. A heat transfer element as defined in claim 1, andin which a. said base portIons of said fins in said certain rows aredisposed in substantially parallel relation to a longitudinal projectionof said base portions of said immediately transversely adjacent fins insaid other rows.
 4. A heat transfer element as defined in claim 1, andin which a. said laterally spaced rows are alternately said certain rowsand said other rows.
 5. A heat transfer element as defined in claim 4,and in which a. said base portions of said fins in said certain rows aredisposed in substantially longitudinal alignment with said base portionsof said immediately transversely adjacent fins in said other rows.
 6. Aheat transfer element as defined in claim 4, and in which a. said baseportions of said fins in said certain rows are disposed in substantiallyparallel relation to a longitudinal projection of said base portions ofsaid immediately transversely adjacent fins in said other rows.
 7. Aheat transfer element as defined in claim 1, and in which a. saidtubular member
 8. A heat transfer element as defined in claim 7, and inwhich a. said laterally spaced rows are alternately said certain rowsand said other rows.
 9. A heat transfer element as defined in claim 8,and in which a. said base portions of said fins in said certain rows aredisposed in substantially longitudinal alignment with said base portionsof said immediately transversely adjacent fins in said other rows.
 10. Aheat transfer element as defined in claim 8, and in which a. said baseportions of said fins in said certain rows are disposed in substantiallyparallel relation to a longitudinal projection of said base portions ofsaid immediately transversely adjacent fins in said other rows.
 11. Aheat transfer element as defined in claim 8, and in which a. said oneface has a plurality of outwardly projecting, substantially parallelspaced ribs thereon, and b. said rows of fins are disposed on respectiveones of said ribs.
 12. The method of making a heat transfer element,comprising a. forming an elongated tubular member having a wall portionwith spaced elongated ribs extending longitudinally of said tubularmember, and b. successively, from one end portion of said tubular membertoward the other end portion thereof,
 13. The method of making a heattransfer element as defined in claim 12, and in which a. the immediatelytransversely adjacent fins on adjacent rows are formed withlongitudinally aligned base portions.
 14. The method of making a heattransfer element as defined in claim 12, and in which a. the fins insaid alternate rows are formed with said base portions thereof disposed